This invention is directed to a gas ignition and temperature holding arrangement for a gas appliance and, more particularly, to a control circuit selectively operable to effect the same. Moreover, this invention is directed to an externally adjustable fluid valve and, more particularly, to a thermal fuel valve readily adaptable for use with natural gas or bottled gas.
In view of the present focus on conservation of energy and, particularly, liquid and gas fuels, it is desirable to eliminate the constantly burning pilot lights often used in gas appliances. In the interest of safety it is also important to control gas flow in gas appliances to avoid such flow without combustion.
The conventional automatic controls for a gas appliance have required relatively complex control systems, usually including one or more solenoid valves, timer switches, and a normally burning pilot light. Also, the usual technique for maintaining the temperature of an oven, for example, at a constant relatively low temperature to keep food warm without appreciable cooking has been to burn gas under control of the thermostatic selector switch, which is adjusted, say, to about 160.degree. to 170.degree. F.
Conventional gas appliance fuel valves are normally designed for use with either natural gas supplied at a four inches pressure or bottled gas, such as liquid propane, supplied at ten inches pressure.